common commands on Linux

#### Tibco ems admin commands

show consumers topic=topic.sample
show consumers queue="queuname"
show connections user="username"

#### sar

sar -W 1 100 : check swap in/out statistics

#### check java class version

$ file ./org/apache/log4j/Appender.class
./org/apache/log4j/Appender.class: compiled Java class data, version 45.3
Or alternatively, using javap from the JDK as @jikes.thunderbolt aptly points out:

$ javap -v ./org/apache/log4j/Appender.class | grep major
major version: 45
And if you are relegated to a Windows environment without either file or grep

> javap -v ./org/apache/log4j/Appender.class | findstr major
major version: 45

#### java

## to check if a 64 bit java

java -d64

java -d32

#### jar

## Create jar file
jar cvf test.jar 1.txt 2.txt

or put 1.txt and 2.txt into test folder, then:

jar cvf test.jar test/*

## extract jar file

jar xf test.jar

It will extract all the files from test.jar and keep all the current directory structure.

so you will see:
test/1.txt
test/2.txt

Suppose you want to extract the TicTacToe class file and the cross.gif image file. To do so, you can use this command:

jar xf test.jar 1.txt

then it will just extract 1.txt from test.jar and put it under test/1.txt.

e.g. you have below jar and it's class file included in the jar:

[lofutpd1@lonlx1060b01:~/release/UTP7.1.0/lib]$ /local/0/sw/java/jdk1.6.0_30/bin/jar tf reconciliation-common-UTP7.1.0.jar | grep DateTime
com/nomura/fitp/reconciliation/DateTimeFormatFilter.class
[lofutpd1@lonlx1060b01:~/release/UTP7.1.0/lib]$

SOmetimes you want to replace that class file in order to test your new fix, you want to replace the class file with newly build class file, so you can do:

/local/0/sw/java/jdk1.6.0_30/bin/jar uf reconciliation-common-UTP7.1.0.jar com/nomura/fitp/reconciliation/FloatValueFormatFilter.class com/nomura/fitp/reconciliation/DateTimeFormatFilter.class

#### grep

1. Only show the matched part
ps -ef | grep service | grep [processUser] | grep -oh "processname=w*"

2. Exclude pattern

grep -v 'pattern'

3. Case insensitive

grep -i

4. include the file name in the grep commands

grep -n 'pattern' file /dev/null

#### tar

tar -cvjf a.tar a.html
tar -xvjf a.tar

-z : gzip(quicker but larger)
-j : bzip2(slower but smaller)

#### ls

ls -lh : human readable size

ls -sSl --block-size=M : sort by size and displayed in mega bytes

ls -sSr --block-size=M : sort by size but displayed in the reverse order, and displayed in mega bytes

use top together with free command:

#### free
free -g
free -m

#### du

du -ah --max-depth=1 : not just directories but also files
du -h --max-depth=1 : just directories

#### wget

wget to get the content of some web page

e.g. wget http://hostname:/directory/filename.txt